The Helical Liquid and the Edge of Quantum Spin Hall Systems


The time reversal invariant quantum spin Hall insulators can support transverse spin transport through the gapless edge modes without the company of the longitudinal charge current. We (with S. C. Zhang et al.) studied the interacting edge states, showing they constitute a new class of the 1D liquid dubbed the helical Luttinger liquid. The fermion doubling theorem proves that the helical Luttinger liquid must arise as an edge effect of the bulk 2D lattices. Strong repulsive interactions can open a gap in the HLL by breaking time reversal symmetry spontaneously. The critical coupling constant of the Kondo problem in the HLL is shifted by interactions, and the Kondo singlet exhibits a spin-current vortex structure.

References and talks

  • Congjun Wu, B. Andrei Bernevig, and Shou-Cheng Zhang, " The Helical Liquid and the Edge of Quantum Spin Hall Systems ", Phys. Rev. Lett. 96 , 106401(2006), see, pdf file .
  • APS March Meeting 2006, Baltimore, Maryland. "Helical Luttinger liquid and quantum spin Hall edge states (PPT)", , Mar. 2006.


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    Last modified: July 15, 2007.